Latest Discussions : HVAC


07:30AM | 02/05/01
Member Since: 02/04/01
3 lifetime posts
For the best energy efficiency, what is the optimum place to put the vents in each room for the new A/C forced heating system?

Ceiling, high on the wall, floors?

We have a flat roof Spanish home built in 1931 with the original Knob & Tube wiring. The appearance from the attic crawl space is that the knob and tube is in good condition with no signs of drying/burning, etc.

The home is 1,346 sqft with 8 rooms, 3 bdrms, and 2 bathrooms - our home has plaster walls and ceilings that we would want protected.

We just received an estimate for a Trane XL1400 Super Efficiency Air Conditioner and a XL90 Forced Air heater unit since we currently have a wall heater with lousy efficiency.

We are sincerely concerned with where the ducting and vents should go. The attic space is only about 3' high and we are putting 11" of insulation up there - so it will be congested. We don't have a basement, but do have a crawl space.

The actual unit is a split system with the one part going in a 3'x3' closet in the laundry room and the A/C unit going outside. So the placement of the unit is not the problem, just the placement of the vents and ducting which will require cutting.

Also, we are in California with the 'energy crisis' - so optimum energy efficiency is key.

We want to do what is absolute best, not necessarily what is 'easiest' for the installer.

Any recommendations or suggestions?

[This message has been edited by gfnrf (edited February 05, 2001).]


04:37PM | 02/06/01
Member Since: 02/05/01
7 lifetime posts
The ideal placement for ducts are in the walls since they are not fighting the extreme
temperatures in the attic or crawl space.
A good installer will know how to place the ducts in the walls. Each room should have a supply line AND a return duct. Not just one central return in the hallway. The supply
line should be installed with one register mounted low towards the floor and one register mounted high towards the ceiling.
The registers have to be dampered so you can shut either one down, diverting the air to the other depending on whether your in heating or cooling mode. For heat, close the upper register and open the bottom, since heat rises. For cooling, close the bottom and open the upper since cool air falls. Make sure you insulate the ducts to avoid conden-
sation on the ductwork in the summer. Also,
I would not let the contractor sell you duct
work with inside insulation. This fiberglass
breaks down and particles will flow through
your home. Its best to use sheetmetal ducts
wrapped with insulating material or insulated
flex-duct. You said you wanted the best not
the easiest... this is it in my opinion, but keep in mind that the walls have to be opened to install the hard pipe ductwork.
I hope this works out.
Your choice in Trane equipment was well made.



06:43PM | 07/14/13
I have a 1972 double wide that I am remodeling. I am putting in new floors and don't want the vents coming out of them, I really want to put one straight pipe down the middle on the ceiling with branches that go off to other rooms. I guess what I am asking is what type and size duct pipe should I use to run from the unit, down the center of the home?
Please help me


04:25PM | 01/20/16
We live in Southern CA, do not need air conditioning. We have owned our 50 year old home for almost 40 years. I read that it may be less expensive to replace ducts than have them cleaned. The upstairs ducts are in the attic and the vents are above doorways(7 ducts). I know we could not replace the downstairs ducts( 4 vents) because the ducts are between the ceiling downstairs and the floor upstairs. The floors are oak plank. We look forward to your reply. Thank you , the Starrs

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